A modeling study of intermediate layers in the midlatitude ionosphere. Ph.D. Thesis
A computational model of the ionosphere is used to investigate the formation of regions of enhanced ionization that appear in the nighttime ionosphere between 100 and 200 km. The basic mechanism that produces intermediate layers is known to be convergent plasma transport due to meridional neutral wind shear. However, this process alone was not thought to be capable of producing the layers without larger than normal nighttime ionization levels in this altitude region. This dissertation is the end result of an attempt to understand more completely the relative contributions of the processes that contribute to intermediate layer formation. The first phase of this research involved a parameter study of various meridional neutral wind characteristics. The results showed that layers formed as a result of both an enhancement in ion density near the peak as well as a depletion of plasma in the region surrounding the peak. Also examined, were the timescales for layer formation and the effects on layers of changes in the properties of the meridional neutral wind system. The addition of a vertical phase velocity to the neutral wind allowed for simulation of the observed motion of the layer down through the ionosphere. The next phase of the research involved examining the effects on the properties of intermediate layers of zonal neutral winds and metallic ions. Interaction between a zonal wind and the meridional wind can affect the position and size of the layers that form. It can also account for the appearance of multiple layers. The model was modified to include metallic ions, in particular Fe(+). This addition provided a chance to investigate how the properties of a layer might vary depending on its composition. Finally, a short study was carried out examining how the winds that create intermediate layers as well as the plasma enhancements themselves affect certain parameters important to the electrodynamics of the ionosphere.
- Research Organization:
- Texas Univ., Dallas, TX (United States)
- OSTI ID:
- 236773
- Report Number(s):
- N-96-21507; NIPS-96-33417; TRN: 9621507
- Resource Relation:
- Other Information: TH: Ph.D. Thesis; PBD: Jan 1994
- Country of Publication:
- United States
- Language:
- English
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